This is unofficial fan content from the Card Colosseum, written for beginners. Every rule below is checked against the official rule manual and FAQ at unionarena-tcg.com.
Union Arena is Bandai's "common rules" trading card game — one set of rules powers decks built from many different anime, so whichever series drew you in (Re:ZERO, Attack on Titan, Jujutsu Kaisen, and more), the engine underneath is the same. That's the pitch: learn one engine, play almost any series.
The Goal
You win by reducing your opponent's Life to 0. Each player starts with 7 Life cards face down, drawn from their own deck. Every clean hit flips one of those Life cards, and when you've taken all 7, you win. There's a second, rarer path: if your opponent's deck runs completely out so they can't draw at the start of their turn, that's also your win.
Your Deck
A legal deck is 50 cards, all from a single series or title. That's Character cards (your fighters), Field cards (persistent effects), and Event cards (one-shot tricks). You may run up to 4 copies of any single card number. Alongside the 50, you bring 3 separate Action Point (AP) cards that refresh each turn.
Two resources matter. AP is your spending pool — playing a card costs AP. Energy is the color your deck needs, generated by cards rested in your Energy Line. Energy isn't consumed when you play a card; it just has to be present. That's why you're building toward a color, not hoarding fuel.
Board Basics
Cards are active (standing vertical) or resting (turned horizontal). Your side has a Front Line, where characters attack and block, and an Energy Line, where cards sit to make colored energy and where Field cards appear. Rested cards return to active at the start of your turn.
Your Turn, Phase by Phase
- Start — turn your rested cards active, add an AP card, and draw. (The first player's very first turn adds an AP card only, with no draw.) The base draw is free, but an extra draw costs 1 AP — and you can only do it once per turn.
- Movement — move any Energy-Line characters up to the Front Line.
- Main — deploy cards and use effects, any order, as many as you can pay for.
- Attack — a Front-Line character attacks; the defender may block with an active Front-Line character. Compare BP: if the attacker's is equal or higher, the attack lands, a Life card flips, and the loser usually goes to the Remove Area.
- End — set cards active again and discard down to 8 cards in hand.
Two wrinkles keep it fun. Life cards flip randomly from your Life pile, and some carry a TRIGGER effect you may optionally reveal — getting hit can hand you an answer, so a Life lead is never safe. And some characters support RAID: lay a card with the RAID keyword on top of a named character to evolve it into a stronger form.
That's the engine — one board, two lines, seven Life cards — now go flip some cards. Craving more Bandai card games? Our sister site Digital Colosseum digs into the Digimon TCG.